Electrical tester



Jm. 22, 1952 M, M HA'SLETT 2,583,424

ELECTRICAL TESTER Filed uarcn 14, 1947 z-lsms-smrr 1 lE/g.' l-Zl .l-O''-02 @l 3 'f5 -o l-oe '/:K

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IN VEN TOR. Mar //z M Has/e zz ATT'CI RN EYB Jan. 22, 1952 M M HAsLET-r2,583,424

m-:c'rRIcAL TESTER Filed March 14, 1947 2 sims-slm 2 IN VENTOR. Mar/'f2//l. Has/eti ATTD RN EYB Pateted Jan. 22, 1952 ELECTRICAL TESTER MartinM. Haslett, Demorest, Ga., assignor to William D. Highll, Bcn TillmanNaval Base,

Application March 14, 1947, Serial No. 734,702

claims. 1

The present invention relates to .electrical testers and moreparticularly to testers adapted for the testing of fractional horsepowermotors, switches, receptacles and .similar items of electricalappara-tus usually present in and around household appliances.

An object of the invention is to include in a compact and unitarydevice, a group of starting relays, capacitors and selective electricalconnections therefor in order that the appropriate unit may 'be rapidly.and conveniently selected.

A further object of the invention is to provide a testing apparatus inwh-ich indicating devices included in the device `may be madeelectrically available for ,external testing such as testing for groundsor for electrical continuity or for determining the vcondition ofenergization of a power outlet.

From another aspect, the invention contemplates the organization into asuitable compact and portable physical arrangement of an assortment ofv.electrical components of various standard sizes together withswitching apparatus permitting the rapid selection of the correct sizefor replacement purposes in an appliance which is being tested.

In accordance with a feature `of lthe invention, various switches andreceptacles are provided, together with suitable test leads which arepreferably connected t0 the testing apparatus by the use o'fconventional attachment plugs and receptac'les. The use of theseconventional connectors minimizes the problem of 'replacement if theexternal testing leads should become lost or damaged.

A further object of the invention is to provide starting facilities formotors of various standard sizes and characteristics 'together withmeasuring apparatus for observation of the line voltage and `linecurrentdrawn by the motor. By the use of such separate 'starting facilities, itis possible to determine vwhether the trouble which is underinvestigation is in the motor itself or in the starting apparatusassociated therewith.

A further object of the invention is to provide testing facilitiescomprising incandescent lamps adapted to serve as a-n approximateindication of the electrical conditions where the accuracy obtained bythe use of instruments is not required.

Other and further objects will become apparent upon reading thefollowing specification together with the accompanying drawings forminga part hereof.

Referring to the drawings:

Fig. 1 shows a schematic circuit drawing .of an embodiment of theinvention.

Fig. 2 shows a diagrammatic representation of external connectingapparatus for use with Fig. l.

Fig. 3 shows a schematic circuit drawing of a modication of theinvention.

Fig. 4 is a diagrammatic representation of external connecting apparatusfor use with Fig. 3.

Referring to Fig. 1, a pair of indicating lamps l-UI and |-02 areprovided which are preferably of the incandescent type.

Power for operation of the tester is derived from conductors I-03 andl-04 which may be terminated in any convenient manner such as anattachment plug (not shown) for connection to the power supply system.Double pole switch l-05 provides for complete disconnection of thetester from the power supply. A fuse I-06 is provided for protectionagainst overloads or short circuits.

In making continuity tests upon apparatus not connected to the powersupply, supply conductors I-03 and |-04 are energized and switch I-05 isclosed. Switch arm l-U'l is then turned to switch terminal I-08. Thiscauses lamp I-l to become illuminated, indicating that the tester isenergized. The three conductor test plug 2-03 shown in Fig. 2 is theninserted in receptacle I-D9. By touching test leads 2--i0 and 2-lltogether, lamp l--02 can be caused to light. Leads 2-l0 and 2-Il areconnected through plug 2-03 and receptacle I-09 to conductors I-IU andI-H respectively. Electrical continuity through any apparatus ofsufficiently low internal impedance can thus be determined. Similarly,test lead 2-12 is connected to conductor l-I2 within the tester.

With the same connections as described above, itis possible to determinethe presence of energy at any desired convenience outlet by attemptingto energize the tester from such outlet. Upon connecting supplyconductors I-03 and I-M thereto, lamp l-DI will light if energy ispresent. if there is no energy present lamp I-OI will not light. Thismay likewise be used to check the condition of fuses by connectingconductors I-03 and I-04 across the fuse under test, although moreconvenient arrangements are included in the tester utilizing the testleads which are more readily adaptable for this purpose.

For the testing of split phase starting single phase motors the threeconductor plug 2-03 is used and test lead 2--l0 is connected to thecommon lead, lead 2--I I is connected to the starting winding of themotor and conductor 2-I 2 is connected to the running winding. Thetester is t kept deenergized. The motor control associated therewith isthen manipulated to cause operation 3 of the motor. Test leads 2 1!) and2-I I, and corresponding conductors l--IU and I-II are thus connectedacross the starting circuit of the motor. If the overload contacts areclosed, this circuit will be energized. Conductors l-II and I-l2, whichare connected to lamp 1 (12, are thus connected across the contactswhich control energization of the running winding. If lamp I-Ul lights,then the overload contacts of the motor control are closed but if lampI-l fails to light the overload contacts are open. If lamp I-DZ lights,then the starting contacts have failed to close. Lamp I--UZ will notburn during the short starting period but will be lighted during therunning period. Under these test conditions, energy for operation of themotor and the indicating lamps is derived from the usual source fromwhich the motor is normally operated, and it is subjected to the actionof the motor lcontrol permanently associated with the motor under test.

If the motor fails to start, indicating that there may be trouble eitherin the motor or in the control, then the separate control equipmentincluded in the tester may be used to localize the trouble. The motorpower supply is then disconnected and the tester is energized asdescribed above. The three conductor plug, 2-03 is connected to themotor as previously described. The tester comprises a plurality ofstarting relays of assorted standard sizes. Switch arm l-Ql is turned toselect the size appropriate for the motor under test. Similarly, aplurality of assorted capacitors of Various standard values ||6 andI-I'I are included in the tester and switch arm I-l8 is turned to selectthe proper capacitor. Switch I-05 is then closed. Lamp l-l will indicatethe condition of the overload switch of the starting relay of thetester, being lighted if the overload contacts are open, andextinguished if they are closed. Lamp I-DZ will similarly indicate thecondition of the starting contacts. If the motor hums but fails to startswitch I -l 9, which is normally in the closed position, is then openedand if lamp |-02 lights it indicates electrical continuity of thestarting and running windings of the motor under test. The rotor of themotor may possibly be blocked by a mechanical fault. The motor may alsobe checked for continuity and possible grounds as described above.

For testing electric range switches, the three conductor test plug 2-53may be used. These switches are ordinarily four position switches with01T, low, medium and high positions controlling a pair of heating unitsof ap `roviriatey equal power consumption. The switch changes from aseries connection of both units, to a single unit, to both units inmultiple, as the switch is turned from low to medium to high. Byconnecting test lead 2- I2 to the common side of the range unit, lampsi-Ul and I-FJZ will be connected across the respective heating units andwill be lighted in accordance with the voltages applied thereto in theVarious positions of the range switch.

By the use of two conductor plug 2-(32, and receptacle 1 2!) any one ofthe capacitors may be selected by switch lever l-i 8 and made availableat the two test leads of plug 2--S2. Where a defective capacitor issuspected, the test leads of plug 2-92 are connected in its place, andwith the test set deenergized, the appropriate capacitor is selected bymeans of switch l-l8. If the test capacitor causes correct operation,then the trouble has been localizedin the capacitor which was replacedby the test capacitor.

A convenience outlet I-2I is included in the test set for the connectionof any desired appliance.

Referring to Fig. 3, a modiiication of the invention is shown in whichthe test lamps have been replaced by electrical measuring instruments.E-i is a combined volt-ammeter and 3-02 is a voltmeter. Double poledouble throw switch 3-93 is connected to cause meter 3-Ul to indicatevoltage in the downward position and to indicate current in the upwardposition. Accordingly, terminal 3-04 is the common terminal andterminals 3-05 and 3-05 are the voltage and current terminalsrespectively.

For testing continuity and for checking for grounds, meter 3-D2 is used.The apparatus to be tested is disconnected from the power supply. Thetester is energized by connecting supply conductors 3-91 and 3-U8 to thecurrent supply and closing double pole double throw switch 3-G9. Fuse3-l3 is provided for protection against overloads and short circuits asin Fig. 1. Switch 3-3 is placed in the downward position and switch arm3-I4 is turned to contact 3-l5. Switch 3l6 is normally left in theclosed position. Switch arm 3-l1 is turned to an off position. Bytouching test conductors 4| l and 4-I2 together with three conductorplug 4-03 inserted in receptacle 3-I9, meter 3-i2 will read the linevoltage. Thus, any desired piece of apparatus may be checked forcontinuity and for grounds within the sensitivity limits of voltmeter3--02 which sensitivity is of importance only in the case of apparatusof high internal impedance compared with the internal resistance of thevoltmeter.

To determine the presence of current at a convenience outlet or to checkthe voltage being delivered to such outlet, neither of the test plugsshown in Fig. fi is used. The tester is energized as above. and switch3-[13 is turned to its down position with switch arm 3--l 4 on position3-I5. With switch 3--9 closed, volt-ammeter 3-0I will indicate the linevoltage being applied to the tester, which in turn is derived from theoutlet under test.

In testing the operation o1 a split phase motor, as described for Fig.l, test leads 4-|0, I-II and 4-l2 are connected to the common, startingand running terminals respectively of the motor under test. With plug4-03 inserted in tester receptacle .1 -IS, and with the testerdeenergized the voltmeter indications of instruments 3-fil and 3-612will correspond to the lamp indications I-fll and I-FZ respectively ofFig. 1. except that quantitative indications will be available.

A plurality of startingr relays 3-2'i- 3-21 and 3-'22 are provided as inthe case of Fig. l, together with an assortment of capacitors 3--23 andS-JM. These are connected for use as described for Fig. l, receptacle3-25 serving for capacitor substitution testing.

tacle SL25 makes the ammeter winding of voltammeter 3-9l available forexternal use subject to the control of switch 3-03. Switch 3--03 permitsthe protection thereof during starting or in the event of an unexpectedshort circuit, using two conductor test plug 4-02. In the case of adevice equipped with the usual attachment plug and cord, receptacle 3-21is used.

While I have described what I believe to be the best embodiments of myinvention, I do not wish to be limited thereto but by the appendedclaims. 'f'

I claim:

1. A tester for electrical appliances comprising a receptacle forreceiving a plug of an electrical appliance, a pair of leads forconnection to a Apower supply, a double pole switch for connecting theinput of said power supply and a double pole switch for controlling theinput of said power supply, connections between said leads and saidswitch, a connection from one pole of said switch to the movable contactof a multipole switch, a plurality of relays connected to the fixedcontacts of said multi-pole switch, an indicating lamp connected betweenthe second pole of said double throw switch and one fixed contact ofsaid multi-pole switch, a connection between said indicating lamp andsaid receptacle, suitable circuits connecting the said relays, saidindicating lamp and receptacle, a second indicating means in thecircuits to show that the circuit between the indicating lamp and relaysis complete, power supply leads in the circuit from the double poleswitch to the receptacle, and the switch between the power supply leadsand circuit adapted to disconnect said tester from said power supply.

2. A tester for electrical appliances comprising a receptacle forreceiving a plug of an electrical appliance, a plurality of relays,circuits connecting said relays with said receptacle, a plurality ofcapacitors, suitable circuits connecting the said capacitors, to thecircuit for said relays and receptacle, indicating means in the circuitsbetween said relays and said receptacle, to show when the circuit isclosed, power supply leads extended from the circuits between theindicating means, relays and capacitors, and a switch between the saidpower supply leads and circuit t0 control the import of said supply tosaid tester.

3. A tester for electrical appliances comprising a receptacle forreceiving a plug of an electrical appliance, a plurality of relays,circuits connecting said relays with said receptacle, a plurality ofcapacitors, suitable circuits connecting the said capacitors, to thecircuit for said relays and receptacle, indicating means in the circuitsbetween said relays and said receptacle to show when the circuits areclosed, power supply leads extended from the circuits between theindicating means, relays and capacitors, a switch between the said powersupply leads and circuits @c between the indicating means, relays andcapacitors, a voltmeter in the circuit between the capacitors andreceptacle and a combination voltammeter in the circuit between saidpower supply leads and said receptacle.

4. A tester yfor electrical. appliances comprising a receptacle forreceiving a plug of an electrical appliance, a plurality of relays,circuits connecting said relays with said receptacle a plurality ofcapacitors, suitable circuits connecting the said capacitors, to thecircuits for said relays and receptacle, indicating means in thecircuits between said relays and said receptacle to show when thecircuits are closed, power supply leads extended from the circuits forsaid relays and said receptacle, a switch between the said power supplyleads and to said last circuits, a voltmeter in said circuits betweensaid receptacle and said power supply leads and sai-d relays and acombination volt-ammeter in said circuit between said power supply andsaid receptacle, said voltmeter being connected in the circuit wherebythe meter is connected across the line only when a relay is closed.

5. A tester for electrical appliances comprising a receptacle forreceiving a plug of an electrical appliance, a plurality of relays,circuits connecting said relays with said receptacle, a plurality ofcapacitors, suitable circuits connecting the said capacitors, thecircuits for said relays and receptacle, indicating means in thecircuits between said relays and said receptacle to show when thecircuits are closed, power supply leads extended from the circuits forsaid indicating means, relays and capacitors, a switch between the saidpower supply leads and said last circuits, a voltmeter in the circuitsbetween the capacitors and receptacle and a combination voltammeter inthe circuit between the power supply leads and the receptacle, saidindicating means including a light bulb and said light bulb andvoltmeter connected in the circuits whereby the light bulb is lightedand the voltmeter actuated when the thermostat of an electric iron isclosed only.

MARTIN M. HASLETT.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,077,626 Mershon Nov. 4, 19131,707,423 Bailey Apr. 2, 1929 1,828,724 Yost Oct. 20, 1931 1,944,090Luhens Jan. 16, 1934 1,984,493 Pierce Dec. 18, 1934 2,018,272 Lunas Oct.22, 1935 2,304,513 Stearns Dec. 8, 1942 2,442,771 Kirkpatrick June 8,1948 OTHER REFERENCES Publication, "Electric Motor Repair, by Rosenberg,Murray Hill Book, Inc., New York, 1946. Pases 1 9 and 44 in theillustrations section.

